渗碳Cr-Mn钢的夹杂分布特性及疲劳强度预测

Prediction for fatigue strength and distribution features of inclusion of carburized Cr-Mn steel

开展渗碳Cr-Mn钢的超长寿命疲劳试验,用扫描电镜观测钢中夹杂物分布、数量及尺寸。基于4种统计方法(SEV,GEV,GPD,EXPGPD)分析渗碳Cr-Mn钢的夹杂尺寸,构建基于内部夹杂尺寸的S-N曲线预测模型。结果表明:预测的特征夹杂尺寸从大到小:EXPGPD、SEV、GPD和GEV,相比从疲劳断口测量的夹杂尺寸,4种方法计算夹杂尺寸偏小。基于构建模型,结合从断口获得的均值夹杂尺寸,预测的S-N曲线可作为中值S-N曲线,预测结果较好。

Ultra-long life fatigue test of carburized Cr-Mn steel was carried out.The distribution,quantity and size of inclusions in steel were observed by scanning electron microscope.Four statistical methods consisting of statistics of extreme values(SEV),generalized extreme values(GEV),generalized pareto distribution(GPD)and exponential generalized pareto distribution(EXPGPD)were used to analysis the inclusion size of carburized Cr-Mn steel,A new model to predict S-N curve using internal inclusion size was developed.The results show that the maximum characteristic inclusion size is estimated by EXPGPD,followed by SEV,GPD and GEV.Compared with the measured inclusion size from the fatigue fracture,the inclusion sizes estimated by four statistical methods are smaller.Based on the new model,the S-N curve predicted from the average value of inclusion size can be used as the median S-N curve which leads to the better prediction result.